Question

public class Group{
@ManyToMany(fetch=FetchType.EAGER, cascade=CascadeType.ALL, mappedBy="groups")
 public Set<User> getUsers() {
  if(users == null)
   return new HashSet<User>();
  else 
   return users;
 }
 public void setUsers(Set<User> users) {
  this.users = users;
 }
}

public class User{

 public void setGroups(Set<Group> groups) {
  this.groups = groups;
 }
    @ManyToMany(cascade = CascadeType.ALL)
 public Set<Group> getGroups() {
  return groups;
 }
}

现在，如果我删除了一个用户，他应该自动从他所在的所有群组中删除。这就是我所期待的。

我得到的是这个丑陋的例外：

> Exception in thread "main"
> org.springframework.dao.DataIntegrityViolationException:
> Could not execute JDBC batch update;
> SQL [delete from USERS where ID=?];
> constraint ["FKB4DD17BD8FCA5D9E:
> PUBLIC.GROUPS_USERS FOREIGN
> KEY(USERS_ID) REFERENCES
> PUBLIC.USERS(ID)"; SQL statement:
> delete from USERS where ID=?
> [23003-143]]; nested exception is
> org.hibernate.exception.ConstraintViolationException:
> Could not execute JDBC batch update
>  at
> org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:637)
>  at
> org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:97)
>  at
> org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:471)
>  at
> org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:754)
>  at
> org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:723)
>  at
> org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:393)
> 2010-10-31 19:41:19.044
> java[28733:903] An uncaught exception
> was raised  at
> org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:120)
>  at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
>  at
> org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
>  at $Proxy22.removeUser(Unknown
> Source)  at
> com.stone.gym.controller.UserController.removeUser(UserController.java:43)
>  at
> com.stone.gym.view.UserView$3.handleEvent(UserView.java:121)
>  at
> org.eclipse.swt.widgets.EventTable.sendEvent(Unknown
> Source)  at
> org.eclipse.swt.widgets.Display.sendEvent(Unknown
> Source)  at
> org.eclipse.swt.widgets.Widget.sendEvent(Unknown
> Source)  at
> org.eclipse.swt.widgets.Widget.sendEvent(Unknown
> Source)  at
> org.eclipse.swt.widgets.Widget.sendEvent(Unknown
> Source)  at
> org.eclipse.swt.widgets.Widget.notifyListeners(Unknown
> Source)  at
> org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown
> Source)  at
> org.eclipse.swt.widgets.Display.readAndDispatch(Unknown
> Source)  at
> com.stone.gym.controller.FrontController.run(FrontController.java:30)
>  at
> com.stone.gym.StoneGym.main(StoneGym.java:21)
> 2010-10-31 19:41:19.045
> java[28733:903] Java exception
> occurred Caused by:
> org.hibernate.exception.ConstraintViolationException:
> Could not execute JDBC batch update
>  at
> org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:71)
>  at
> org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
>  at
> org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:254)
>  at
> org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:266)
>  at
> org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:172)
>  at
> org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:298)
>  at
> org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
>  at
> org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1001)
>  at
> org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:339)
>  at
> org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
>  at
> org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:54)
>  at
> org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:467)
>  ... 19 more Caused by:
> org.h2.jdbc.JdbcBatchUpdateException:
> Referential integrity constraint
> violation: "FKB4DD17BD8FCA5D9E:
> PUBLIC.GROUPS_USERS FOREIGN
> KEY(USERS_ID) REFERENCES
> PUBLIC.USERS(ID)"; SQL statement:
> delete from USERS where ID=?
> [23003-143]  at
> org.h2.jdbc.JdbcPreparedStatement.executeBatch(JdbcPreparedStatement.java:1101)
>  at
> org.apache.commons.dbcp.DelegatingPreparedStatement.executeBatch(DelegatingPreparedStatement.java:231)
>  at
> org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:48)
>  at
> org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:247)
>  ... 28 more

Answer 1

现在，如果我删除了一个用户，他应该自动从他所在的所有群组中删除。这就是我所期待的。

我怀疑您在删除给定的User之前没有正确更新Group和User之间的“链接的两面”，因此连接表中的约束违规异常水平。这样的事情：

for (Group group : user.getGroups()) {
     group.getUsers().remove(user);
}
em.remove(user);

另外，我想知道你为什么要级联所有操作（你想在删除用户时删除组吗？）

Answer 2

您需要将Group的inverse设置为true，删除用户将删除相对关系。但是，如果您的用户级联是全部，则组也将被删除。所以将其更改为save-update。

帕斯卡的建议是一种更好的方法。明确删除关系始终是首选。

Answer 3

您可以使用Hibernate网站（http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/#entity-mapping-association）中描述的此技术。请务必从群组实体中的 @ManyToMany 中删除 mappedBy 。

 public class Group{
 @ManyToMany(fetch=FetchType.EAGER)
 @JoinTable(name = "groups_users",
        joinColumns = @JoinColumn(name = "groups_id"),
        inverseJoinColumns = @JoinColumn(name = "users_id"))
 public Set<User> getUsers() {
  if(users == null)
   return new HashSet<User>();
  else 
   return users;
 }
 public void setUsers(Set<User> users) {
  this.users = users;
 }
}

public class User{

 public void setGroups(Set<Group> groups) {
  this.groups = groups;
 }
 @ManyToMany
 @JoinTable(name = "groups_users",
        joinColumns = @JoinColumn(name = "users_id"),
        inverseJoinColumns = @JoinColumn(name = "groups_id"))
 public Set<Group> getGroups() {
  return groups;
 }
}

从ManyToMany集合中删除成员会抛出org.h2.jdbc.JdbcBatchUpdateException

3 个答案: